Termites, and related pests, constitute a significant economic threat in a modern society. While conventional insecticides, typically chlorinated hydrocarbons such as chlordane, DDT, aldrin, dieldrin and BHC can be effectively utilized to eradicate these pests, such insecticides pollute water, contaminate soil, and are toxic to many life forms. Chlordane is the only chlorinated hydrocarbon that has not yet been banned, principally because a suitable substitute having its effectiveness has yet to be found. However, it still accumulates in the environment and causes food chain elimination since, for instance, an earthworm may be resistant to its poison, but the bird which consumes many such earthworms may die or be rendered infertile. A environmentally inactive chemical is thus needed to obviate food chain problems. While the chlorinated hydrocarbon insecticides are economical to produce, the cost of the resulting environmental cleanup makes their use expensive in the long run. Thus, there exists a substantial need for new environmentally safe and effective pesticides.
For a pesticide to be effective against termites and related pests it may have a somewhat delayed onset of activity. Termites typically feast upon a food supply and then return to their nest and regurgitate the food to be shared by those occupying the nest. Thus, a pesticide which instantly destroys the feeding termites has absolutely no effect upon those hatching on the nest. While the feeding termites are affected, those in the nest continue to multiply and thus the infestation remains.
Termiticidal compositions which meet the foregoing criteria have been prepared by Applicant and are disclosed in Prestwich, U.S. Pat. No. 4,452,793 and Prestwich, U.S. Pat. No. 4,455,441.
While these termiticidal compostions represent a substantial improvement over the prior art, they still require to be adsorbed upon suitable carriers.
These compounds show excellent differential toxicity. That is to say, that the level of toxicity, i.e., LD.sub.50 (for termites), is substantially greater than that for mammals. In the interests of further environmental safety, it would be desirable to provide attractant termiticidal compositions which are chemically bound to the carrier rather than merely adsorbed thereon, in order to further reduce the possibility of environmental contamination by leaching, small though this possibility may be.
Since cellulose is the favorite source of nourishment for termites, it would be desirable to chemically modify cellulose in a manner which would meet these criteria. In designing such a termiticide however care must be taken to ensure that the modified material would be substantially indistinguishable, in a physical sense, from cellulose itself so that the termites would feed upon it without realizing its toxic nature. Furthermore, the modification of the cellulose could be such as to maintain the delayed toxicity factors which have made the previously disclosed Prestwich compositions commercially desirable.